Charging techniques for solid-state batteries in portable electronic devices

ABSTRACT

The disclosed embodiments provide a system that manages use of a solid-state battery in a portable electronic device. During operation, the system monitors a temperature of the solid-state battery during use of the solid-state battery with the portable electronic device. Next, the system modifies a charging technique for the solid-state battery based on the monitored temperature to increase a capacity or a cycle life of the solid-state battery. To modify the charging technique based on the monitored temperature, the system may increase a charge rate of the solid-state battery if the temperature exceeds a first temperature threshold. On the other hand, the system may maintain the charge rate of the solid-state battery if the temperature does not exceed the first temperature threshold.

CROSS REFERENCE TO RELATED APPLICATIONS

This Non-provisional application is a continuation of U.S.Non-Provisional application, application Ser. No. 13/354,179, filed onJan. 19, 2012 and issued as U.S. Pat. No. 9,197,096 on Nov. 24, 2015,the entire contents of which is herein incorporated by reference.

BACKGROUND

Field

The disclosed embodiments relate to batteries for portable electronicdevices. More specifically, the disclosed embodiments relate to chargingtechniques for solid-state batteries in portable electronic devices.

Related Art

Rechargeable batteries are presently used to provide power to a widevariety of portable electronic devices, including laptop computers,tablet computers, mobile phones, personal digital assistants (PDAs),digital music players and cordless power tools. The most commonly usedtype of rechargeable battery is a lithium battery, which can include alithium-ion or a lithium-polymer battery.

Lithium-polymer batteries often include cells that are packaged inflexible pouches. Such pouches are typically lightweight and inexpensiveto manufacture. Moreover, these pouches may be tailored to various celldimensions, allowing lithium-polymer batteries to be used inspace-constrained portable electronic devices such as mobile phones,laptop computers, and/or digital cameras. For example, a lithium-polymerbattery cell may achieve a packaging efficiency of 90-95% by enclosingrolled electrodes and electrolyte in an aluminized laminated pouch.Multiple pouches may then be placed side-by-side within a portableelectronic device and electrically coupled in series and/or in parallelto form a battery for the portable electronic device.

Recent advances in battery technology have also led to the developmentof solid-state batteries, in which electrodes and a thin solidelectrolyte are layered on top of a non-conducting substrate. Becausethe solid electrolyte takes up less space and/or weighs less than theliquid electrolyte of a comparable lithium-ion and/or lithium-polymerbattery, the solid-state battery may have a higher energy density thanthe lithium-ion and/or lithium-polymer battery. In addition, thesolid-state battery may be safer and/or more reliable than conventionallithium-ion and/or lithium-polymer batteries. For example, the use of anon-flammable, solid electrolyte in the solid-state battery may allowthe solid-state battery to sidestep liquid electrolyte hazards such asspilling, boiling, gassing, and/or fires. Consequently, solid-statebatteries may improve the safety, reliability, form factor, and/orruntime of portable electronic devices.

SUMMARY

The disclosed embodiments provide a system that manages use of asolid-state battery in a portable electronic device. During operation,the system monitors a temperature of the solid-state battery during useof the solid-state battery with the portable electronic device. Next,the system modifies a charging technique for the solid-state batterybased on the monitored temperature to increase a capacity or a cyclelife of the solid-state battery. To modify the charging technique basedon the monitored temperature, the system may increase a charge rate ofthe solid-state battery if the temperature exceeds a first temperaturethreshold (e.g., 25° Celsius). On the other hand, the system maymaintain the charge rate of the solid-state battery if the temperaturedoes not exceed the first temperature threshold.

In some embodiments, the system further increases the charge rate of thesolid-state battery if the temperature exceeds a second temperaturethreshold (e.g., 45° Celsius) that is higher than the first temperaturethreshold.

In some embodiments, increasing the charge rate of the solid-statebattery involves at least one of increasing a charge current of thesolid-state battery, and increasing a charge voltage of the solid-statebattery.

In some embodiments, the portable electronic device is at least one of amobile phone, a laptop computer, a tablet computer, and a portable mediaplayer.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a cross-sectional view of a battery cell in accordance withthe disclosed embodiments.

FIG. 2 shows a schematic of a system in accordance with the disclosedembodiments.

FIG. 3 shows an exemplary plot in accordance with the disclosedembodiments.

FIG. 4 shows an exemplary plot in accordance with the disclosedembodiments.

FIG. 5 shows a flowchart illustrating the process of managing use of asolid-state battery in a portable electronic device in accordance withthe disclosed embodiments.

FIG. 6 shows a computer system in accordance with the disclosedembodiments.

In the figures, like reference numerals refer to the same figureelements.

DETAILED DESCRIPTION

The following description is presented to enable any person skilled inthe art to make and use the embodiments, and is provided in the contextof a particular application and its requirements. Various modificationsto the disclosed embodiments will be readily apparent to those skilledin the art, and the general principles defined herein may be applied toother embodiments and applications without departing from the spirit andscope of the present disclosure. Thus, the present invention is notlimited to the embodiments shown, but is to be accorded the widest scopeconsistent with the principles and features disclosed herein.

The data structures and code described in this detailed description aretypically stored on a computer-readable storage medium, which may be anydevice or medium that can store code and/or data for use by a computersystem. The computer-readable storage medium includes, but is notlimited to, volatile memory, non-volatile memory, magnetic and opticalstorage devices such as disk drives, magnetic tape, CDs (compact discs),DVDs (digital versatile discs or digital video discs), or other mediacapable of storing code and/or data now known or later developed.

The methods and processes described in the detailed description sectioncan be embodied as code and/or data, which can be stored in acomputer-readable storage medium as described above. When a computersystem reads and executes the code and/or data stored on thecomputer-readable storage medium, the computer system performs themethods and processes embodied as data structures and code and storedwithin the computer-readable storage medium.

Furthermore, methods and processes described herein can be included inhardware modules or apparatus. These modules or apparatus may include,but are not limited to, an application-specific integrated circuit(ASIC) chip, a field-programmable gate array (FPGA), a dedicated orshared processor that executes a particular software module or a pieceof code at a particular time, and/or other programmable-logic devicesnow known or later developed. When the hardware modules or apparatus areactivated, they perform the methods and processes included within them.

FIG. 1 shows a cross-sectional view of a battery cell 100 in accordancewith the disclosed embodiments. As shown in FIG. 1, battery cell 100includes a substrate 102, a cathode current collector 104, a cathodeactive material 106, an electrolyte 108, an anode active material 110,and an anode current collector 112.

More specifically, FIG. 1 shows a cross-sectional view of a solid-statebattery cell 100. The components of battery cell 100 may be formed bydepositing layers of different materials onto substrate 102 and/or oneanother. For example, substrate 102 may correspond to a non-conductingsubstrate such as mica, polyamide, and/or polyether ether ketone (PEEK).A vacuum deposition technique may be used to deposit cathode currentcollector 104 as a layer of platinum and/or gold onto substrate 102 andanode current collector 112 as a layer of copper onto substrate 102.Next, a sputtering technique may be used to deposit a lithium compoundcorresponding to cathode active material 106 onto cathode currentcollector 104, along with a thin film of lithium phosphorus oxynitride(LiPON) corresponding to a solid electrolyte 108 over cathode currentcollector 104, cathode active material 106, substrate 102, and/or anodecurrent collector 112. A layer of lithium may then be thermallyevaporated onto the LiPON to form anode active material 110. Finally,battery cell 100 may be sealed in a protective package 114 such as apolymer frame and/or flexible pouch.

FIG. 2 shows a schematic of a system in accordance with an embodiment.The system may provide a power source to a portable electronic device,such as a mobile phone, personal digital assistant (PDA), laptopcomputer, tablet computer, portable media player, and/or peripheraldevice. In other words, the system may correspond to a battery thatsupplies power to a load 218 from one or more components (e.g.,processors, peripheral devices, backlights, etc.) within the portableelectronic device. For example, the battery may correspond to asolid-state battery that includes one or more cells 202-206, such asbattery cell 100 of FIG. 1. As shown in FIG. 2, the system also includesa set of switches 210-214, a main power bus 216, a systemmicrocontroller (SMC) 220, a charger 222, and a set of monitors 224-228.

In one or more embodiments, cells 202-206 are connected in a seriesand/or parallel configuration with one another using main power bus 216.Each cell 202-206 may include a sense resistor (not shown) that measuresthe cell's current. Furthermore, the voltage and temperature of eachcell 202-206 may be measured with a thermistor (not shown), which mayfurther allow a battery “gas gauge” mechanism to determine the cell'sstate-of-charge, impedance, capacity, charging voltage, and/or remainingcharge. Measurements of voltage, current, temperature, and/or otherparameters associated with each cell 202-206 may be collected by acorresponding monitor 224-228. Alternatively, one monitoring apparatusmay be used to collect sensor data from multiple cells 202-206 in thebattery.

Data collected by monitors 224-228 may then be used by SMC 220 to assessthe state-of-charge, capacity, and/or health of cells 202-206. Monitors224-228 and SMC 220 may be implemented by one or more components (e.g.,processors, circuits, etc.) of the portable electronic device.

In particular, SMC 220 may correspond to a management apparatus thatuses the data to manage use of the battery in the portable electronicdevice. For example, SMC 220 may correspond to a management apparatusthat uses the state-of-charge of each cell 202-206 to adjust thecharging and/or discharging of the cell by connecting or disconnectingthe cell to main power bus 216 and charger 222 using a set of switches210-214. Fully discharged cells may be disconnected from main power bus216 during discharging of the battery to enable cells with additionalcharge to continue to supply power to load 218.

Along the same lines, fully charged cells may be disconnected from mainpower bus 216 during charging of the battery to allow other cells tocontinue charging.

Those skilled in the art will appreciate that reductions in batterycapacity may result from factors such as age, use, defects, heat, and/ordamage. In particular, charging and discharging of a conventionallithium-ion or lithium-polymer battery may cause a reaction ofelectrolyte with cathode and anode material. The reaction may bothdecrease the capacity of the battery and cause swelling throughenlargement of the electrode and/or gas buildup inside the battery.Moreover, the reaction may be accelerated if the battery is operated athigher temperatures and/or continuously charged at high charge voltages.For example, a lithium-polymer battery that is operated at 25° Celsiusand/or charged at 4.2V may reach 80% of initial capacity and increase inthickness by 8% after 1050 charge-discharge cycles. However, use of thesame battery at 45° Celsius and/or a charge voltage of 4.3V may decreasethe capacity to 70% of initial capacity and increase the swelling to 10%after 1050 charge-discharge cycles.

On the other hand, the electrolyte conductivity of a solid-state batterymay increase with temperature. In turn, the solid-state battery mayexperience better performance and/or a longer cycle life at higheroperating temperatures. For example, a solid-state battery may have acapacity of 1500 mAh and a cycle life of 1000 charge-discharge cycles ifthe solid-state battery is operated at 25° Celsius and a capacity of1600 mAh and a cycle life of 1200 charge-discharge cycles if thesolid-state battery is operated at 45° Celsius.

In one or more embodiments, the system of FIG. 2 includes functionalityto facilitate use of a solid-state battery with the portable electronicdevice. During use of the solid-state battery with the portableelectronic device, monitors 224-228 and/or SMC 220 may monitor thetemperature of the solid-state battery. SMC 220 may then modify acharging technique for the solid-state battery based on the monitoredtemperature to increase the capacity and/or cycle life of thesolid-state battery.

More specifically, SMC 220 may modify the charging technique byincreasing the charge rate of the solid-state battery every time thebattery's temperature exceeds a temperature threshold. To increase thecharge rate, SMC 220 may increase the charge current and/or chargecurrent of the solid-state battery. Conversely, SMC 220 may maintain thecharge rate of the solid-state battery if the battery's temperature doesnot exceed a temperature threshold. Solid-state battery charge rates andcharge times as a function of temperature are discussed in furtherdetail below with respect to FIGS. 3-4.

For example, SMC 220 may set temperature thresholds of 25° Celsius, 45°Celsius, 60° Celsius, and 70° Celsius for the solid-state battery andbegin charging the solid-state battery at an initial charge rate of 0.5°C. Each time the battery's temperature exceeds one of the temperaturethresholds (e.g., due to heat buildup from charging the battery and/oruse of the portable electronic device), SMC 220 may increase the chargerate by 0.5° C. On the other hand, if the battery's temperature remainsrelatively constant during charging, SMC 220 may maintain the chargerate until the battery is fully charged. Finally, if the battery'stemperature drops below a temperature threshold, the battery's chargerate may be reduced by 0.5° C.

By charging the solid-state battery faster at higher temperatures, SMC220 may facilitate efficient charging of the battery. In addition, SMC220 may perform such charging without adversely impacting the cycle lifeand/or capacity of the battery, thus maximizing use of the battery withthe portable electronic device. In other words, SMC 220 may facilitateuse of the portable electronic device by optimizing the use of thesolid-state battery with the portable electronic device.

FIG. 3 shows an exemplary plot in accordance with the disclosedembodiments. More specifically, FIG. 3 shows a plot of a charge rate 302for a solid-state battery as a function of the battery's temperature304. As shown in FIG. 3, charge rate 302 may increase with temperature304 to accommodate the solid-state battery's increased electrolyteconductivity at higher temperatures. For example, charge rate 302 may beset to 0.5° C. at 25° Celsius, 1° C. at 35° Celsius, 1.5° C. at 45°Celsius, and 3° C. at 60° Celsius.

In addition, charge rate 302 may be varied based on a set oftemperatures thresholds for the solid-state battery. For example, chargerate 302 may be increased each time temperature 304 exceeds atemperature threshold of 25° Celsius, 35° Celsius, 45° Celsius, or 60°Celsius. Alternatively, charge rate 302 may be modified in a morefine-grained manner (e.g., whenever temperature 304 changes by 1°Celsius) to better reflect the curve in the plot.

FIG. 4 shows an exemplary plot in accordance with the disclosedembodiments. In particular, FIG. 4 shows a plot of a charge time 402 fora solid-state battery as a function of temperature 404. As shown in FIG.4, charge time 402 may decrease with temperature 404 to reflect theincrease in the solid-state battery's charge rate with temperature shownin FIG. 3. For example, charge time 402 may be two hours at 25° Celsius(e.g., at a 0.5° C. charge rate), one hour at 35° Celsius (e.g., at a 1°C. charge rate), ⅔ of an hour at 45° Celsius (e.g., at a 1.5° C. chargerate), and ⅓ of an hour at 60° Celsius (e.g., at a 3° C. charge rate).As a result, the solid-state battery may perform differently fromconventional batteries (e.g., lithium-ion batteries, lithium-polymerbatteries) by charging faster at higher temperatures withoutexperiencing degradation.

FIG. 5 shows a flowchart illustrating the process of managing use of asolid-state battery in a portable electronic device in accordance withthe disclosed embodiments. In one or more embodiments, one or more ofthe steps may be omitted, repeated, and/or performed in a differentorder. Accordingly, the specific arrangement of steps shown in FIG. 5should not be construed as limiting the scope of the embodiments.

First, the temperature of a solid-state battery is monitored during useof the solid-state battery with the portable electronic device(operation 502). Next, the monitored temperature may be used to modify acharging technique for the solid-state battery. In particular, thetemperature may be compared to a temperature threshold (operation 504)to determine if the temperature exceeds the temperature threshold. Forexample, the temperature may exceed a first temperature threshold aftercharging of the battery is initiated and a second temperature thresholdthat is higher than the first temperature threshold after use of theportable electronic device is increased (e.g., by a processor-intensiveapplication). If the temperature does not exceed a temperaturethreshold, the charge rate of the solid-state battery is maintained(operation 506).

If the temperature exceeds the temperature threshold, the charge rate ofthe solid-state battery is increased (operation 508) to facilitateefficient charging and use of the battery. For example, the charge ratemay be increased by increasing the charge current and/or charge voltageof the solid-state battery. The increased charge rate may utilize theincreased electrolyte conductivity of the solid-state battery at highertemperatures, thus increasing the capacity and/or cycle life of thesolid-state battery while reducing the charge time of the solid-statebattery. In addition, the increase in charge rate may further increasethe temperature of the solid-state battery, thus enabling subsequentincreases in both the charge rate and temperature and furtherfacilitating efficient charging of the solid-state battery.

The solid-state battery may continue to be charged (operation 510). Ifcharging of the solid-state battery is to continue, the temperature ofthe solid-state battery is monitored (operation 502), and a chargingtechnique for the solid-state battery is modified based on the monitoredtemperature to increase the capacity and/or cycle life of thesolid-state battery (operations 504-508). For example, the solid-statebattery's charge rate may be increased every time the solid-statebattery's temperature exceeds a new temperature threshold. On the otherhand, the solid-state battery's charge rate may be maintained if thesolid-state battery's temperature plateaus and/or remains relativelyconstant. Such charging of the solid-state battery may continue untilthe solid-state battery is fully charged.

FIG. 6 shows a computer system 600 in accordance with an embodiment.Computer system 600 includes a processor 602, memory 604, storage 606,and/or other components found in electronic computing devices. Processor602 may support parallel processing and/or multi-threaded operation withother processors in computer system 600. Computer system 600 may alsoinclude input/output (I/O) devices such as a keyboard 608, a mouse 610,and a display 612.

Computer system 600 may include functionality to execute variouscomponents of the present embodiments. In particular, computer system600 may include an operating system (not shown) that coordinates the useof hardware and software resources on computer system 600, as well asone or more applications that perform specialized tasks for the user. Toperform tasks for the user, applications may obtain the use of hardwareresources on computer system 600 from the operating system, as well asinteract with the user through a hardware and/or software frameworkprovided by the operating system.

In one or more embodiments, computer system 600 provides a system formanaging use of a solid-state battery in a portable electronic device.The system may include a monitoring apparatus that monitors atemperature of the solid-state battery during use of the solid-statebattery with the portable electronic device. The system may also includea management apparatus that modifies a charging technique for thesolid-state battery based on the monitored temperature to increase thecapacity and/or cycle life of the solid-state battery. For example, themanagement apparatus may increase the charge rate of the solid-statebattery whenever the temperature exceeds a temperature threshold ormaintain the charge rate if the temperature does not exceed thetemperature threshold. The increase in charge rate may decrease thecharge time of the solid-state battery without adversely affecting thecycle life or capacity of the solid-state battery.

In addition, one or more components of computer system 600 may beremotely located and connected to the other components over a network.Portions of the present embodiments (e.g., monitoring apparatus,management apparatus, etc.) may also be located on different nodes of adistributed system that implements the embodiments. For example, thepresent embodiments may be implemented using a cloud computing systemthat monitors and manages solid-state batteries in remote portableelectronic devices.

The foregoing descriptions of various embodiments have been presentedonly for purposes of illustration and description. They are not intendedto be exhaustive or to limit the present invention to the formsdisclosed. Accordingly, many modifications and variations will beapparent to practitioners skilled in the art. Additionally, the abovedisclosure is not intended to limit the present invention.

What is claimed is:
 1. A computer-implemented method for managing charging of a solid-state battery in a portable electronic device, comprising: monitoring a temperature of a solid-state battery during charging of the solid-state battery; and modifying a charge rate by increasing at least one of a charge current of the solid-state battery and a charge voltage of the solid-state battery when the monitored temperature exceeds a first temperature threshold, wherein the first temperature threshold is in a range of 45 degrees Celsius and above.
 2. The computer-implemented method of claim 1, further comprising modifying the charge rate when the monitored temperature exceeds a second temperature threshold, wherein the second temperature threshold is higher than the first temperature threshold, wherein the second temperature threshold is 60 degrees Celsius and above.
 3. The computer-implemented method of claim 2, further comprising increasing the charge rate by 1.5 C when the monitored temperature exceeds the first temperature threshold and does not exceed the second temperature threshold.
 4. The computer-implemented method of claim 2, further comprising modifying the charge rate by 3 C when the monitored temperature exceeds the second temperature threshold.
 5. The computer-implemented method of claim 1, further comprising decreasing the charge rate by 0.5 C when the monitored temperature drops below the first temperature threshold.
 6. A system for managing use of a solid-state battery in a portable electronic device, comprising: a monitoring apparatus configured to monitor a temperature of a solid-state battery during charging of the solid-state battery; and a management apparatus configured to modify a charge rate by increasing at least one of a charge current of the solid-state battery and a charge voltage of the solid-state battery when the monitored temperature exceeds a first temperature threshold, wherein the first temperature threshold is in a range of 45 degrees Celsius and above.
 7. The system of claim 6, wherein the management apparatus is configured to modify the charge rate when the monitored temperature exceeds a second temperature threshold, wherein the second temperature threshold is higher than the first temperature threshold, wherein the second temperature threshold is 60 degrees Celsius.
 8. The system of claim 7, wherein the management apparatus is configured to increase the charge rate by 1.5 C when the monitored temperature exceeds the first temperature threshold and does not exceed the second temperature threshold.
 9. The system of claim 7, wherein the management apparatus is configured to modify the charge rate by 3 C when the monitored temperature exceeds the second temperature threshold.
 10. The system of claim 6, wherein the management apparatus is configured to decrease the charge rate by 0.5 C when the monitored temperature drops below the first temperature threshold.
 11. A non-transitory computer-readable storage medium, readable by a processor and comprising instructions stored thereon to cause the processor to: monitor a temperature of a solid-state battery during charging of the solid-state battery; and modify a charge rate by increasing at least one of a charge current of the solid-state battery and a charge voltage of the solid-state battery when the monitored temperature exceeds a first temperature threshold, wherein the first temperature threshold is in a range of 45 degrees Celsius and above.
 12. The non-transitory computer-readable storage medium of claim 11, wherein the instructions further comprise instructions to cause the processor to modify the charge rate when the monitored temperature exceeds a second temperature threshold, wherein the second temperature threshold is 60 degrees Celsius and above.
 13. The non-transitory computer-readable storage medium of claim 12, wherein the instructions further comprise instructions to cause the processor to increase the charge rate by 1.5 C when the monitored temperature exceeds the first temperature threshold and does not exceed than the second temperature threshold.
 14. The non-transitory computer-readable storage medium of claim 12, wherein the instructions further comprise instructions to cause the processor to modify the charge rate by 3 C when the monitored temperature exceeds the second temperature threshold.
 15. The non-transitory computer-readable storage medium of claim 11, wherein the instructions further comprise instructions to cause the processor to decrease the charge rate by 0.5 C when the monitored temperature drops below the first temperature threshold.
 16. A portable electronic device, comprising: a set of components powered by a solid-state battery; a monitoring apparatus programmed to monitor a temperature of the solid-state battery during charging of the solid-state battery; and a management apparatus programmed to modify a charge rate by increasing at least one of a charge current of the solid-state battery and a charge voltage of the solid-state battery when the monitored temperature exceeds a first temperature threshold, wherein the first temperature threshold is in a range of 45 degrees Celsius and above.
 17. The portable electronic device of claim 16, wherein the management apparatus is configured to modify the charge rate when the monitored temperature exceeds a second temperature threshold, wherein the second temperature threshold is in a range of 60 degrees Celsius and above.
 18. The portable electronic device of claim 17, wherein the management apparatus is configured to increase the charge rate by 1.5 C when the monitored temperature exceeds the first temperature threshold and does not exceed than the second temperature threshold.
 19. The portable electronic device of claim 17, wherein the management apparatus is configured to modify the charge rate by 3 C when the monitored temperature exceeds the second temperature threshold.
 20. The portable electronic device of claim 16, wherein the management apparatus is configured to decrease the charge rate by 0.5 C when the monitored temperature drops below the first temperature threshold. 